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Black Hole Masses of Active Galaxies with Double-peaked Balmer Emission Lines
We have obtained near-IR spectra of five AGNs that exhibit double-peakedBalmer emission lines (NGC 1097, Pictor A, PKS 0921-213, 1E0450.30-1817, and IRAS 0236.6-3101). The stellar velocity dispersions ofthe host galaxies were measured from the Ca II λλ8494,8542, 8662 absorption lines and were found to range from 140 to 200 kms-1. Using the well-known correlation between the black holemass and the stellar velocity dispersion, the black hole masses in thesegalaxies were estimated to range from 4×107 to1.2×108 Msolar. We supplement theobservations presented here with estimates of the black holes masses forfive additional double-peaked emitters (Arp 102B, 3C 390.3, NGC 4579,NGC 4203, and M81) obtained by other authors using similar methods.Using these black hole masses, we infer the ratio of the bolometricluminosity to the Eddington luminosity,(Lbol/LEdd). We find that two objects (Pictor Aand PKS 0921-213) have Lbol/LEdd~0.2, whereas theother objects have Lbol/LEdd<~10-2(nearby, low-luminosity double-peaked emitters are the most extreme,with Lbol/LEdd<~10-4). The physicaltimescales in the outer regions of the accretion disks (atr~103GM/c2) in these objects were also estimatedand range from a few months for the dynamical timescale to severaldecades for the sound crossing timescale. The profile variability inthese objects is typically an order of magnitude longer than thedynamical time, but we note that variability occurring on the dynamicaltimescale has not been ruled out by the observations.Based on observations carried out at Cerro Tololo Inter-AmericanObservatory, which is operated by AURA, Inc., under a cooperativeagreement with the National Science Foundation.
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